I lost a set of keys.然后是用 Is this yours?还是Are these yours?

I lost a set of keys.然后是用 Is this yours?还是Are these yours? this,yours,keys,set,is,of,the,lost,in,and,found,case（?）连词成句 Here is （）?Are these yours.A.a set of found:a set of keys Are these yours call jenny at 284-5486.换 （Is） the set of keys yours?为什么用Is 不用Are? 是there is a set of keys还是there are a set of keys? Is this yours?和Are these yours?的答句有哪些 What _____ these keys?Are these yours? （These three) pieces of luggage is yours.用is对吗?还是用are.为什么?并且 是Some of the money is yours还是Some of the money are yours 这件衣服是你的吗,翻译成英语 是 Are these clothes yours 还是 Is this clothes i lost a set of keys ,i can't find them 还是it.